Struggling Dutch team Spyker have been forced to postpone the introduction of their revamped F1 car.
Spyker lie bottom of the 2007 constructors' championship
They were hoping to unveil their new B-spec model at this weekend's Turkish Grand Prix in Istanbul.
But the upgraded car failed the strict rear-impact test meaning they must pass a re-examination at the Italian Grand Prix at Monza on 9 September.
Spyker chief technical officer Mike Gascoyne said: "We're confident we'll pass with no problems next week."
Gascoyne revealed that an unexpected failure of the rear crash test, possibly due to the batch of material used, caused their crash test failure.
And he added: "It's obviously very disappointing to delay the launch, especially considering the hard work everyone at the factory and track has put in.
"These tests are quite rightly very stringent and difficult to pass, but we did not expect to have a problem as the structure is very similar to the A-spec one.
"We will now concentrate on doing the best we can this weekend. As we were aware we had a problem we brought two A-spec cars, as well as two B-spec cars.
"We will not have any problems switching back, but it's just disappointing not to have the performance increase as planned."
The firm has been weighing up selling some or all of its Formula One team as part of a refinancing plan.